I have one similar to this, and it is fine. It doesn't have the swimming space of other tank designs, but it will certainly do. You may have to baffle the current from the filter if it disturbs your betta. I think more leafy silk plants would help as well--make sure the plastic stems do not have any rough spots--also, you should fluff the leaves out so the betta does not get caught trying to swim through the stems. Feeling around inside the decor piece, if you have not already, is also a good idea. Some resin and ceramic pieces can have sharp areas inside them, particularly around the seams. You can scrape off any sharp pieces of the plant or the resin piece with a metal file--I usually use a metal nail file, but don't expect a nail file to stand much abuse. :)
Now that you have a new tank I suggest researching the nitrogen cycle and how to cycle a tank using the fishless method.
Last edited by Adastra; 06-25-2010 at 04:35 PM.